linux-kernel - [PATCH 5/7] can: m_can: fix CAN state in system PM

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Message-Id: <20250812-m_can-fix-state-handling-v1-5-b739e06c0a3b@pengutronix.de>
Date: Tue, 12 Aug 2025 19:36:55 +0200
From: Marc Kleine-Budde <mkl@...gutronix.de>
To: Chandrasekar Ramakrishnan <rcsekar@...sung.com>, 
 Vincent Mailhol <mailhol.vincent@...adoo.fr>, 
 Patrik Flykt <patrik.flykt@...ux.intel.com>, 
 Dong Aisheng <b29396@...escale.com>, Fengguang Wu <fengguang.wu@...el.com>, 
 Varka Bhadram <varkabhadram@...il.com>, Wu Bo <wubo.oduw@...il.com>, 
 Markus Schneider-Pargmann <msp@...libre.com>, 
 Philipp Zabel <p.zabel@...gutronix.de>
Cc: linux-can@...r.kernel.org, linux-kernel@...r.kernel.org, 
 kernel@...gutronix.de, Marc Kleine-Budde <mkl@...gutronix.de>
Subject: [PATCH 5/7] can: m_can: fix CAN state in system PM

A suspend/resume cycle on a down interface results in the interface
coming up in Error Active state. A suspend/resume cycle on an Up
interface will always result in Error Active state, regardless of the
actual CAN state.

During suspend, only set running interfaces to CAN_STATE_SLEEPING.
During resume only touch the CAN state of running interfaces. For
wakeup sources, set the CAN state depending on the Protocol Status
Regitser (PSR), for non wakeup source interfaces m_can_start() will do
the same.

Fixes: e0d1f4816f2a ("can: m_can: add Bosch M_CAN controller support")
Signed-off-by: Marc Kleine-Budde <mkl@...gutronix.de>
---
 drivers/net/can/m_can/m_can.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index 310a907cbb7e..149f3a8b5f7e 100644
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -2507,12 +2507,11 @@ int m_can_class_suspend(struct device *dev)
 		}
 
 		m_can_clk_stop(cdev);
+		cdev->can.state = CAN_STATE_SLEEPING;
 	}
 
 	pinctrl_pm_select_sleep_state(dev);
 
-	cdev->can.state = CAN_STATE_SLEEPING;
-
 	return ret;
 }
 EXPORT_SYMBOL_GPL(m_can_class_suspend);
@@ -2525,14 +2524,14 @@ int m_can_class_resume(struct device *dev)
 
 	pinctrl_pm_select_default_state(dev);
 
-	cdev->can.state = CAN_STATE_ERROR_ACTIVE;
-
 	if (netif_running(ndev)) {
 		ret = m_can_clk_start(cdev);
 		if (ret)
 			return ret;
 
 		if (cdev->pm_wake_source) {
+			u32 reg_psr;
+
 			/* Restore active interrupts but disable coalescing as
 			 * we may have missed important waterlevel interrupts
 			 * between suspend and resume. Timers are already
@@ -2544,6 +2543,9 @@ int m_can_class_resume(struct device *dev)
 			if (cdev->ops->init)
 				ret = cdev->ops->init(cdev);
 
+			reg_psr = m_can_read(cdev, M_CAN_PSR);
+			cdev->can.state = m_can_can_state_get_by_psr(reg_psr);
+
 			m_can_write(cdev, M_CAN_IE, cdev->active_interrupts);
 		} else {
 			ret  = m_can_start(ndev);

-- 
2.50.1